Electrotype magnetic printing plate

ABSTRACT

An electrotype printing plate member attachable to a supporting saddle member or cylinder by magnetic forces. The print member includes a thin metallic shell, in which a printing surface is carried, and may be filled by a thermoplastic material, and backed by a ferrous material such as steel; or the shell may be filled directly by a magnetic material. Either one or both members may include a layer of ferrous material such as steel. Either one or both members may include a layer of a permanently magnetized material formed by dispersion of anisotropic particles of ferromagnetic material in a binder. If both members include a layer of ferrous material the magnetized material may lie independently between the members.

[ June 28, 1974 ELECTROTYPE MAGNETIC PRINTING PLATE [76] Inventor: Clarence R. McElreath, PO. Box

13149, Houston, Tex. 77019 [22] I Filed: Dec. 28, 1970 [21] Appl. No.: 101,631

[52] U.S. Cl 101/382 MV, lOl/395 [51] Int. Cl B4lf 27/02 [58] Field of Search 101/382 MV, 395

[ 56] References Cited UNITED STATES PATENTS 1,377,504 5/1921 Novotny l01/395 3,039,389 6/1962 Meese et al. 101/382 MV X 3,180,259 4/1965 McKay l0l/378 3,217,641 11/1965 Goffrepo 101/395 3,228,133 l/1966 Baermann 40/142 A 3,447,460 6/1969 Vincent et a1. 101/395 X 3,464,134 9/1969 Franklin 40/142 A 3,616,145 10/1971 Clifton.. 101/382 MV X 3,670,646 6/1972 Welch 101/382 MV Primary ExaminerClyde 1. Coughenour Attorney, Agent, or Firm-Torres & Berryhill [5 7] ABSTRACT An electrotype printing plate member attachable to a supporting saddle member or cylinder by magnetic forces. The print member includes a thin metallic shell, in which a printing surface is carried, and may be filled by a thermoplastic material, and backed by a ferrous material such as steel; or the shell may be filled directly by a magnetic material. Either one or both members may include a layer of ferrous material such as steel. Either one or both members may include a layer of a permanently magnetized material formed by dispersion of anisotropic particles of ferromagnetic material in a binder. If both members include a layer of ferrous material the magnetized material may lie independently between the members.

4 Claims, 4 Drawing Figures PATENTEDJUH28 m4 3820.460

Radius: O /o 00 x/sz FIG. 2 F163 Clarence R, Mc E/reazh INVENTOR I CmJo-m ATTORNEY ELECTROTYPE MAGNETIC PRINTING PLATE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to the printing art. More specifically it concerns letterpress printing plates and their attachment to plate cylinders of a rotary printing press, or other printing equipment.

2. Description of the Prior Art For many years, when volume and quality are primary considerations, electrotype printing plates have proved to produce the best letterpress work available. In conventionally made electrotype printing plates, a thin outer printing shell is first made by an electroplating process, whereby a thin layer of usually copper or nickel is deposited in a mold. The mold has depressions forming the printing surface to be printed. When the thin shell is removed it also has depressions on its inner surface. To be suitable for placing on a a plate cylinder, these depressions must be filled and the thin shell filled up by a backing material conventionally called Electrotype Metal which contains tin (i 3 percent), lead (i 94 percent) and antimony 3 percent). Such a combination is heavy and accumulates a total weight which restricts rotary press speeds. The placing or replacing of such plates on the press is a tedious, time consuming operation. For rotary presses, the printing plates are curved so as to conform to the plate cylinders. These electrotype printing plates, as the composite is called, are then mechanically attached to the cylinder. For example, see US. Pat. No. 2,549,226. The weight of the plates and means of attachment result in quite a bit of effort and time when the plates are changed, as they frequently are. In addition, as can be seen, these plates are quite cumbersome and expensive to make.

In an effort to reduce expense, weight and attachment time, many attempts have been made to work out a more satisfactory printing plate design. For example, US. Pat. No. 2,977,876 discloses a printing plate or saddle which may be used for subsequent service with other printing plates. US. Pat. Nos. 2,788,743 and 3,180,259 disclose methods of electromagnetic attachment in which the printing plates are attached to a cylinder, magnetized by electromagnets. None of the improvements in this area have proved to be the ultimate, as evidenced by continued developments.

SUMMARY OF THE INVENTION The present invention comprises an outer print member, carrying the electrotype shell, attachable to a backing member or saddle by a thin sheet of oriented particles of permanently magnetic material in a flexible matrix or binder, such as rubber or plastic. The magnetic sheet may be bonded to either the shell member or the saddle or merely placed therebetween. Such a construction allows the saddle to be mechanically attached to a plate cylinder for use with a number of print members, which may be replaced simply by pulling the print members away from the saddle member. This greatly reduces changeover time. In addition, if it is desired, for any reason, to return to a conventional type plate, the saddle member may be removed in the conventional way.

BRIEF DESCRIPTION OF THE DRAWINGS For a detailed description of the invention, reference will be made to the attached drawings in which:

FIG. 1 is a perspective view of a print member and a saddle member for use on a printing press plate cylinder, according to a preferred embodiment of the inventron;

FIG. 2 is a partial cross section of a print member and saddle member showing in detail a preferred embodiment of the invention;

FIG. 3 is a partial cross section of a print member and saddle member showing in detail an alternate embodiment of the invention; and

FIG. 4 is a partial cross section of a print member and saddle member illustrating one means of aligning the members according to a preferred embodiment of the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring first to FIG. 1, there is shown an arcuate print member 10 and an arcuate saddle member 20 for attachment to a plate cylinder (not shown). These members are curved to conform to a cylindrical surface so as to permit use with a conventional plate cylinder. The saddle may be mechanically attached to the plate cylinder in a conventional manner known in the art. Although the invention was primarily developed for use with a rotary press, it is not so limited lt could be adapted to other shapes and forms for use with flat or other type presses. Furthermore, the saddle member 20 could be eliminated by attaching the print member directly to the plate cylinder.

The outer surface of the print member 10 is the electrotype shell 11 in which the printing surface is carried. This shell 11 may be formed, by the conventional electroplating process, of materials such as copper and nickel. Lying underneath the thin shell 11 is one or more backing materials 12, as may be more clearly understood hereafter. The saddle member 20 made up of one or more layersof material, is a relatively stronger and heavier member than print member 10.

Either the print member 10 or the saddle 20 may comprise at least one layer of ferromagnetic particles which are magnetically oriented and dispersed in a flexing the print member and saddle to be held-together by a a strong magnetic force when they are placed in contact with one another. If both the print member 10 and saddle 20 comprise a ferrous layer, the magnetic material may be mounted without bonding, as a separate and independent sheet therebetween. As stated before, the saddle member 20 could be eliminated by attaching the print member 10 directly to the plate cylinder, or bed in the case of a flat press.

Referring also now to FIG. 2, the construction of a preferred embodiment of the invention may be more fully understood. The print member 10 may comprise an outer metallic shell 11, a core of thermoplastic material l3 and an inner sheet of steel 14. The thermoplastic material 13 fills the depressions in shell 11. The steel plate 14 may be bonded to thermoplastic material 13 at 15 in any suitable manner. The saddle 20 may comprise an outer layer of magnetic material 21, an intermediate layer of steel 22 and an inner layer of lighter material such as aluminum 23. These materials are bonded together in any suitable manner at 24 and 25.

Magnetic material 21 comprises many particles of a ferromagnetic material dispersed in a rubber or plastic matrix to form a flexible sheet of magnetic material. It has been found that, if the crystals of a ferromagnetic material are oriented in a particular direction, its magnetic properties are much greater than the same-material whose crystals are not oriented. The oriented material is said to be anisotropic whereas the-nonoriented material is said to be isotropic. Prior to this discovery, dispersion of ferromagnetic particles in a flexible material matrix resulted in poor magnetic properties. However, even though the ferromagnetic particles are diluted by dispersion in a polymeric matrix or binder, such as rubber or plastic, they may exhibit magnetic properties comparable to a bulk mass of isotropic ferromagnetic particles, if the dispersed particles are oriented to become anisotropic. Although they are not as strongly magnetic as ferromagnetic materials, ferrimagnetic materials may also be used. The term ferromagnetic as used in the description and claims which folthe saddle. In other cases it might be more desirable to leave the flexible magnetic sheet as an unbonded separate component which may be placed on either the saddle 20 or shell member prior to bringing of the print and saddle members together.

Still another embodiment of the invention is shown in FIG. 3. The thin shell 31 is filled by the magnetic material 32 which is bonded thereto in such a manner as to fill the depressions in the shell 31. This print member 30 may then be attached to a saddle member 40 which comprises a sheet of steel 41 which may or may not be supported by another material such as 42. Furthermore, with a print member such as 30, sheet 41 may be replaced by another layer of flexible magnetic material (not shown) in which case the backing material 42 may or may not be magnetic.

As seen in FIG. 1 and in more detail in FIG. 4, the

edge of the saddle member 20 may be provided with a locating tongue 27, for example, by turning up a tab cut from steel plate 22. A corresponding notch 17 may be cut in the edge of shell plate 10. The plates may then be easily brought together in proper alignment, through cooperation of tongue 27 and notch 17.

Thus, it can be seen that the present invention provides a solution to many of the problems inherent in previous printing plate designs. The print and saddle member construction permits rapid change of printing plates, increasing press production time and allows alternate use of conventional printing plates. All of this is done without change or special adaptation of conventional rotary press plate cylinders.

Although several embodiments of the invention have been disclosed herein, other variations may be made by one skilled in the art, without departing from the spirit of the invention. For example, the invention could be used with print members of a type other than the electrotype. The scope of the invention is limited only by the claims which follow.

I claim:

1. A printing means comprising a main support member having an outer surface; a saddle member con-- nected to said outer surface; a magnetic member formed of a unitary flat flexible magnetic material secured to said saddle member; and a magnetically at-- tractable printing plate member magnetically adhered to said magnetic member by the magnetic force of the magnetic member; said printing plate member comprising a metallic printing surface backed by a thermoplas: tic material and a layer of ferrous material.

2. A printing means as set forth in claim 1 in which said flat flexible magnetic material comprises anisotropic particles of ferromagnetic material dispersed in a polymeric matrix.

3. A printing means as set forth in claim 1 in which said metallic printing surface is an electroplated surface of a material selected from a group consisting of: copper, nickel, compounds of copper, and compounds of nickel.

4. A printing means as set forth in claim 1 in which said saddle member comprises a layer of ferrous material backing said magnetic material and a layer of aluminum backing said ferrous material. 

2. A printing means as set forth in claim 1 in which said flat flexible magnetic material comprises anisotroPic particles of ferromagnetic material dispersed in a polymeric matrix.
 3. A printing means as set forth in claim 1 in which said metallic printing surface is an electroplated surface of a material selected from a group consisting of: copper, nickel, compounds of copper, and compounds of nickel.
 4. A printing means as set forth in claim 1 in which said saddle member comprises a layer of ferrous material backing said magnetic material and a layer of aluminum backing said ferrous material. 